Internal combustion engine



Sept- 5, 1939- 5. K. HOFFMAN ET A]. 2,172,100

INTERNAL COMBUSTION ENGINS v Fi1ed Nov. 5, 1934 6 SheetsSheet 1 Sept. 5,1939. 5. K.- HOFFMAN El' AL 2,172,100

INTERNAL COMBUSTION ENGIHE Filed Nov. 5, 1934 6 SheetsSheet 2 Sept. 5,1939.

5. K. HOFFMAN :r AL 2,172,100

INTERNAL COMBUSTION ENGIRE 6 Sheet-Sheet a Filed Nov. 5. 1954 Sept. 5,'1939. 7

5. K. HFFMAN E! AL INTERNAL COMBUSTION ENGINE Filed 'Nov. 5, 1934 '6SheetsSheet 4 Sept. 5, 1939.

5. K. HOFFMAN ET AL INTERNAL COMBUSTON ENGINE Filed Nov. 5, 1934 6Sheets-Sheet 5 Sept. 1939- 5. K. HOFFMAN ET AL 2,172,100

.INTENAL COMBUSTIONNGINE Filed Nov. 5, 1934 -6 She ets-Sheet 6 ,ma's L1939 v UNITED STATES z,m,mo

{PATENT orrics by niesne assignments, to Aviation MannactuflngCorporation. Chicago, 111., a corporation oi. Dehwfl.r

pplicaflon November .5, 1934, Serial No. 351,49.

3 Gains.

lem of control design as well as pilotage. The gyroscopic moments whichare impressed upon the airplane due to the rotation '01? elements in theengine when the airplane is flying on a curved path, are factors whichrender the reVolution of the engines in opposite directions,respectively, desirable. Whentwo engihes are operated with oppositedirections et rotation, the torque reaction and the gyroscopic momentsare cancelled out and thus simplify the design and construction .of theplane, as well as its pilotage. These conditions make it desirable touse engines driven in opposite directions or to. maire the direction ofrotation 01 the engine selective or reversible wlth ,25 the minimumamount of labor and exchange of parts. In some 'englnes,,such as thos'eusingtwo 4 banks of cylinders and cam shafts for the intake and exhaustvalves'ior each' bank, respectively, the direction et rotation can bereversed. by a 30 simple intrchange o! cam shafts and, perhaps,

some other miner changs, such asthose necessary in the electric wiringfor ignition timing. In consequence, the direction of rotation'of theengine itself -may be selective for this purpose. 35 Rotary auxiliaryequipment or accessories for interna] combustion engines, for example,the supercharger, fuel charger, starter, impeller for cooling fiuid andlbricant circulating or forcing means are unidlrectional l'or operationwith an 40 engine in a single direction and, in consequence, are notusually adapted for operation in opposite or both directions.

In aircraft operations, it is necessary to mainequipment for 4 tainspare parts and auxiliary 45 reserve and in the p'rocess of overhaul. omeet these requirements, it ls necessary, when unidirectional auxiliaryequipment is used, to maintain a supply of spare equipment for enginesdriven in right or left directions, in order to have 50 available spareauxiliary equipinent for either type of'engine. This involves doubiingthe number of spare aux fliary equipment, which is nor- .mally kept inreserve,- to meet the requirements for both right and left engines, andhalves the 55' production of each design of the auxiliary equipment, onnocount of the necessity of prodcing it for operation in bothdirections. and doubles the investment in spare parts.

The present invention contempiates the use with engines operated ineither direction or in. il

which the direction of rotation is selective, of uni-directional rotaryauxiliary equipmnt, which is operable with an engine operating in eitherdirection, so that it may be operatively associated without structuralchanges with the sam engine .10 when its direction of rotation 13reversed. or with any engine, regardless of its direction et rotation.The primary0biect of the invention is to pro vide a poWer plant whichiiic hids an,interflal combustion engine and uni-directional rotaryauxiliary equipment or accessories, such as a super-charger, fuelcharger, starter, impeller for cooling fluid and lubricant circulatingor forcing meansof the rotary type, which are Operable with an engineoperating in either right or left diree- -20 tions. By providing drivingmechanism for the auxiliary equipment which can be selectively changedto operate it in the single direction for which it is designed, frcm enengine designed to operate ineither direction, it becomes unnecessary toprovide two types of spare equipment dsigned for operation with bothright and left engines, respectively.

Another object of the invention is to provide means for: operatinguni-directional rotary auxiliary equipment which can, with minimumlabor,

\ be opratively connected to either a right or leit engine, to drive theequipment in the single direction for which it is designed.

Another object of the invention is to provide a simple and eflicient.driving mechanism for the auxiliaries of an internal combustion enginewhich is readily and easily selectively reversible. Anotherobiect of theinvention isto provide simle and.efcient means for driving' the aux- 40iliaries from the crankshait-of an internal combustion engine.

Another object of the invention-1s to provide improved mechanism fordriving an -inipeller from the engine. Other objectsoi the inventionwill appearirom the det9.lfed description. The invention consists in theseveral novel l'eatures hereinafter set forth and more particularlydefined by claims at the conclusion hereof.

In the drawings:h Fig. 1 is a plan et an engineembodying the invention;Fig. 2 is,a rear view of the engine. Fig. 3 is an inverted plan 01! aportion of the engine. Fig. 4 is a vertical ulqngitudinal Sectionthrough the rear end of the engine and the driving mechanism for theauxiliary equipment. Fig.

5 is a transverse section on line 55 of Fig. 4. Fig. 6 is a longitudinalsection illustrating the reversible sha;ft set for operating theauxiliary equipment when the engine is rotatabie in one direction. Fig.7 is a similar view illustrating the reversible shaft in its alternateposition to drive the auxiliary equipment in the samedirection from areversely operating engine. Fig. 8 is a, vertical section throughthe-hydraulic driving mechanism for the compressor of the equipment.Fig. 9 is 9. section on line 99 of Fig. 8. Fig. 10 is a transversesection illustrating the gearing and hydraulio drives for one of theimpellers, Fig. 11 is a detail of the spider for supporting the drivegears co-axial withthe crank-shaft.

The invention is exempiified in an internal combustion engine used fordriving an aircraft or other propeller. The engine comprises a cas"- ingor crank-case 20, opposed banks of power cylinders 2 l, containingpistons, respectively, connected to the oranks of a power-shat 23 whichis journaled in the crank-case and extended at its front end 23 to drivea propeller, intake manifolds l9, exhaust manifolds i8, supportingframes H, and other usual elements of an internal combustion engine,such as valves, injectors or carbureters and ignition devices. all ofwhich may be of any suitable construction, as well known in the art.

The auxiliary quipment of the engine com prises a compressor B forsupercharging the en-v gine, an electric starter C, connectable toinitially drive the crank-shaft, a rotary pump D for forcing coolingfluid to the cooling means for the engine, a fuei-charging pump E, afuel-circulating pump F, and a pump G for circulating lubrieant throughthe lubricating system of the engine, all of which are ofthenidirectionai rotary type or connected to the engine so that eachwill in a bearing 2 3 in the crankcase which is formed et sectionsdivided vertiCally. The auxiliary equipment is driven from the rear endof said shaft 23. The driving mechanism for the auxiliary equipment iscarried in a rearward extension 26 of the crank-case 20 and .a sectionalcasing or housing, which is carried by the engine case andcomprises ahead 25 and a member 21, both of which are removably secured to the rearend of the extension 26.

The.mechanism for driving the auxiliary equipment comprises a hollowshaft 28, the front end of which extends into an axial socket 29 in therear end of the crank-shaft 23, which is provided with internalsplnes 29to receive splines on said shaft 28; a shaft 3l, coaxial with the shaft28 and journaled in a bearing 32, carried by the head 25; a beveled gear33, integral with shaft 3| provided with a forwardly extending.

hub 34 which is provided with interna] splines 31 for engagement withsplines on the shaft 28 and which is Journaled in the hub of a bearingspider 35, secred at 35 in the case-extension 26; a mating beveled gear36 coaxial with gear 33 and provided with a hub extendhxg into andjournaled in the hub of spider 35; and a set of beveled intemediategears i, il, 62, which mesh with both 01? the gears 33, 38. Gears Mi, 4|and 42 transmit power'between gears 33, 36 and are adapted to driveeither of said latter -gears from the other and, together with gear 33,are adaptkd to drive the uni-directional auxiliary equipment. ashereinafter set forth.

Shaft 28 is reversible from end to end in the socket 29 and is providedwith splines 30 and 80 As shown in Fig. 6, splines' 86 on shaft 28interfit'with the splines '29 in the socket 29 of the crank-shaft andsplines 3010 will interfit with the splines 311 on gear 38 to drive saidgear in one direction. When gear 33 is driven in the direction of therotation of the engine, said gear 33 and the gears in, M and Mi, throughwhich power is transmitted to all of the auxiliary equipment, will bedriven in the proper direction for which the atixiliary equipment isdesigned, and

gear 86 will idle in a direction reverse to that of gear 33. When theshaft 28 is reversed end to end, as shown in Fig. 7, the splines 3!) ofshait 23 will interfit with the splines 29 on the crankshaft and splines30 will interfit with the splines 3'! on'the gear 36, whereupon thegear. 36 will be driven in, and gear 33wili be driven oppositely to, thedirection of the rotation of the engine. When the auxiliary equipment isoperable to be driven in the direction in which it will be drivenby gear33 rotating in the same direction as the crank-shait, the reversibleshaft 28 will be placed in the position shown in Fig. 6. 'When the di'rection of the engine is reversed or the auxiliary reversely rotatingcrank-shaft, through shaft 28 is connected to drive gar 33. 'Byreversing th shaft .28 to drive either of beveled gears 33, 36

according to the direction et rotation 01 the engine, the auxiliaryequipment driven from gears sa, :30, M and #2 will be driven in thesingle direction for which it is designed and.con-

nected to the engines so it will funtion properly with a crank-shaftbeingdriven either to the right or to'the left This feature adapts theauxfliary equipment for selective functioning with either a left orrighthand engine.

The geard2 between beveled gears 33, 36 remains constantly in mesh withgears 33, 36, and by so doing the intermediate beveled .gears 40, dl andM are prevented from backing out of engagement with either of thebeveled gears 33, 36 so that increase of tooth stresses and wear i.sprevented. A thrust plate 38, with a bearing'39, contiguous to the outerface of gear 36. la provided to prevent axialmovement of gear 36. Theaxes of the three beveled intermediate gears.l0, M and 42 are radialfrom the axis of the gears 33, 36- to provide compact mechanism fordriving the auxiliary equipment.

Beveled intermediate gear is provided with an integraishait 43 which ismounted in a sectional head which is removably secured in the extension26 of the crank-case 20 and is adapted to be driven by an electricstarter C which may be of any suitable construction. A

ratchet clutch 46 is provided on the outer end of shaft 43 and isadapted to be driven by 8 ccaxial clutch wheel 41 on the. starter.Clutch wheei 37 is adapted to be automatically coupled with clutch wheel38 when the starter is operated to start the motor, as-wellunderstood inthe art. Since gear 40 meshes constantly with gears 33, 38, thedirection in which the cran]:-

the. reveflibie 33. V

:Menreyersible shaft 33 is-connected tofldrive scat 33, thestarter.thmugh gear 33, will drive the cranksbatt in one direction, andwhen shaft 33 is coupled to-xear 33, the direction of rotation 01 thecrankshflftb sear u will be in the oppbs ite direction. "As a result.the starter mechanism isadapted to drive the crankshaftto start w theengiiigeaccording to'the selected direction of rotation of the engineand by the reversal of shatt -23. This exempliflesymeans operated by auni-directionaily operated starter. by which the crank-sbatt may bedriven in opposite directions tien .01 the starter.

tdConespond with the seiected direction otrota- Beveed intermediate gear3l, which meshes with ber'reled gears 33, 33, is mounted in 8.sectionaihead 33 which is removably secured in 'housing-member 21 and isprovided with anintegral shaft 33. A pinion Il is splined tothe outerend of shaft 33 and mesh'es vith an inter- :nal gear 32 on tiie shatt 33of the. tuel-chaming pump E which is removably secured against the outerend of the head 43 and with said head to hoin-member 21. 33 is ottherotary type and may be of any suitable construction. as weil understoodin the art.

Since beveled 'gar 3| meshes constantly with oppositely rotatabie gears33, 33, the pump 33 will,be driven, either by the gear 33 orthe gear 33,in the same direction while the crank-shatt 33 is operated in eitherdirection through the properlyseleoted position of shaft 23 so it wiiloperate either one or the other of said opposite- V 'Ihis Exemplifiesdriving mechanism for a rotary fuei-charglng pump which is operable inthe same direction Irom a motor rotatingin either direction.

li gear-33 is flxed to the shaft 33 of beveled geai- ,i8xenclosed in thehead 33, and in adapted to drive the fuei-circrflating pump F throughsuitablegring 'from gear 33. Since shafl; 33, j to which gear 33 isfixed, is driven in the same direction, from the engine operating ineitirer direction'updn the proper setting of the reversible shafi: 23the circulating pump 33 will be driven in the same direction at alltimes to function with eitber a right or left-ha'nd engine.

Beveled gear 32. which also meshes -with oppositely iotating beveledgears 33, 33, has an intgral shatt n, which is journaled in a sect'ionalhead 33, which is mounted in the cylindriczai member 33 of'the caninsextension 23. Shatt 33is connctedto drive a coaxiai shatt V 31 -also'mourited in head 39 through an' over running or one-way. spring clutch32 mounted -inth ci indrical recass in the contignousends .0! saidshatts, so as to permit shait 3l to be driven in one directionindependently oi= the shaft-33, intermediate se'ars 33, 31; 32 and the.geais33;'33.

A shaft'33 for operating-the coolant pump d and coaxial with shafts 3!and u. a Joumaled in a head 33 which is removablr secured to a member 01the case-extension 23, and has .its

upperj end splined to' shatt 3l. .The

comprises a casin 33 co'nsisting o! a member integraliy{qrmed with' thehead 34. a cover '33.

and a r0tor.br impeiler 41 for circulating t iuid throgh the enclinsmeans of the exigine.flxed .to

thezlower and or shatt n, which extends into ,."casinz'3l. 'The,casinzbas a dependinginiet duct 33 and.ontlet ducts 31 for -deliverinx cool-The fl1elcharging pump gear 32, which drives the implier for the-confinsfluid, isaitemately driven by gears 33, 33,when

the engine is' rotating in opposite directions, the impeller-wfli alwaysbe drivenin the same direction' and tunction to deliver'the coolinzfluid to' Shait 33 is sealed byparkings 33,

the engine. glands '39, and a spring 13 interposed between theglands. v

A gear 1l -is formed on the hoilow shaft 3l. which is driven by theover-rnnning or one-way clutch 32 and serves to drive the lubricant pumpG. Gear 1! hieshes with an idler gear 12 which is mounted on a stud 13which is carried by a head gwhicb is removahlysecured to the bottom ofthe casing-extension 23. which contains an 011 Samp from which lubricantcari flow top pump G. A

Idler gear 12 meshes with a geai 13 which is flxed to the drive-shaft 13of the punipC which is iliustrzated as'the three--stage type, each stagecomprisjng'a pair of intermeshing gears 11, 13. Two of the stages may beconnected to scavenge the lubricating oil from'the craiflacase and onemay be used to supply lubricating oii under pres sure to the lbricatingsystem of the engine. The case g of pump G isremovabiy'mounted on thehead 'g which is secured to the casing-extensien 23. Since thelubricating pump G is driven irom beveled gear 32 through shafts 33, 3l,gears H, 12, 13, and gear 42 is driven in the same direction whiie.theengine is driven in either direction, through the selective adjustmentof shaft23, the gear pump G will be driven in the samedirection at alltimes, to function with the engine while it is driven in eitherdirection or with engines -rotating in opposite directions.

Th compressor B for forcing air to supercharse the motor comprises a.casing bwhich is secured to the back of a housing-member 21 which .isflxed to the rear and of the crank-case extension 23, and an impeller orrotor 3l with blades 32 for drawing air from a valve-controiled intake33, and propelling it from the casing b into the manifold b whichdehversthe air to the intakes of the engine cylinders, as wellunderstood in the art. Impeiler 8l 15 driven from beveledgear 33 so thatit will always be driveri in the same direction while the crankshatt .ofthe moto! is rotated in either direction.

" The driving mechanism'for the compressor B,

comprises a gear 33 which is splined to the hub 3l which is integraiwith gear 33 and removabiy secured on said hub by a screw e0llar 3|; aset,

o! three pinions 83 which mesh with gear 83; a

set of three helical gears 93; a hydraulic drive between each of thepinions 93 and gear 93; a.

, nuir complementry casing-sections 90, SI, each o'i which isprovidedtwith suitable radial vanes 33 and a concave circuiar web 93 andan anmflar bandz33-lapping the pelipheries of said cas1nse e itns d p srel ti e snpp se so that-the gears13 wiii bedrivn from gear -33 andsections 93 throngh the hydraulic medium contained in the sections. Eachcasing section a is integrai m: one of the pinidns I! and these.

are splined t0 rotate with a. hoilow shaft 31 which is Journaled in abeaflng 33 inthe head 23 and a, bearing l3 inhousing member 31,. ,Eachhelicai gear 93 is integral with the casing-stcfion 39 and their commonhub is journaled to rotate on the hollow shaft d'3. A thrust bearing 93is provided between said hub and bearing 89. Each baud 92 is providedwith a lining of suitable material to permit slippage between thecasingsections 90, al to rsiiiently drive the impeller B.

Pinion 94 and gears 93 are provided with helical teeth so proportionedthat the tangentia-tooth load will develop an axial component which willapproximateiy balance the axiai thrust produced by the impelier 8l. Thisthrust is due to the reduction in static pressure developed by theincrease in velocity through the impeiler. duction in pressure over thearea of the operative face of the impeller creates a force acting tomove shaft 95 in the direction of bearing 96. The opposed axialcomponent of the helical teeth on gears 96 is designed to neutralize orreduce this force and thereby minimize the axial loads on beaflngs 96,96 thus reducing their friction. Helicai pinion 93, which meshes withhelical gears transfers the axial thrust of the imllier to the gears onthe hydraulic drive. This is the economical place to absorb the trustbeeause it is divided through the gea'rs associated With the hydraulicdrive which run at a much slower speed than the impeller itself.

Since the super-charge absorbs a substantial percentage of the enginepower when not more directly driven with shaft 28 and gear shaft 3H, itis advantageous to drive it through three bev eled gears si), il and 42;which are equidistantiy spaced around the axis of the crankshaftandshaft 28, thereby minimizing the toth stresses and the radial loadsand the friction on the bearing surfaces. To assist in equalizing thetooth loads, any backlash of the gears 40, dl and 62 is taken up byshims 98.

Engine iubllcating oil -under pressure is delivered to duct m in head 25from the lubricant circulating pump, and from said duct lubri-- cant issuppiied to the hearings for gears 33, 36 in spider 35.

Each hydraulic drive is supplied with engine lubricating oil, underpressure, through a port MI in the head 25. A plunger lli2 loaded by aspring m3 prevents excessive leakage and loss of pressure at the pointwhere the 011 is introduced into the shaft 81. From port Il the oilpasses through button m2 into shaft 81 and through port 104 in saidshaft and duct l to the hydraulic drive casing. The hydraulic drives arenormally subjected to oil pressure to compensate wiil always be drivenin the same direction while the engine is rotated in opposite direction.

A shaft DE, coaxial with the crank-shaft and shait 28, is spiined at I0!to the shaft 31 of gear 33. This shaft extends outwardly through thehollow shaft 95'which carries and drives the im pelier8i and has itsouter end journaled in a bearing H18 carried by the casing I9 of thesupercharger. The outer end of this shaft has a splined socket "19 whichis adapted to receive a The reshaft for any additional auxiliarymechanism deslred. A cap Il is secured to enclose the end of shait mewhen it is not in use.

A hollow shaft MI 15 journaled in a head 2 which is removably secured inthe housing-member 21 and carries at its inner end an integral beveledgear us which meshes with a beveled gear 4 integral with the shaft 6lwhich is driven through the over-running spring clutch 62. The outer endof shaft III is provided with a splined socket 5 to adapt it to receivethe shaft of a smail electric motor. The purpose of the overrunningclutch 62 andthis shatt HI is to permit the impeller for the coolingfluid and the 1ubri cant pumps which are also driven by shaft 6l,

for starting. It is also possible to preheat the- ]ubricating oil by anelectric heater and operate the pump G to circulate warm oil through theengine. When it is necessary in starting the engine. the liquid enteringthe impeller 65 is heated and the lubricating oil is heated and theshait I i I is operated by an electric motor or other suitable meanswhich will cause said impelier and the lubricant pump to supply heatedliquid and warm oil to the engine preparatory to starting it. Duringthis operation the impeller D and Dump G will be operated independentlyof the engine and the other auxfliary equipment, because theover-running clutch 62 Will permit shaft 8l to rotate independentlyofshaft 58. This exemplifies means for driving the impeller for thecooiant, and the lubricant pump, independently of the engine forstarting purposes and which will be continuously operated by the enginewhen it is run.

In operation, the engine drives the entire auxiliary equipmentthroughshaft 28. If the engine is set to operate, or is operative in onedirection, the shaft 28 wiil be placed in the position shown in Figs. 4and 6, to drive the gear 33 by means of sDline 31. The enre auxiliaryequipment will then be driven in the proper direction for which it isdesigned. When the engine is set so as to be, or is operated in thereverse direction, the shaft 28 will be reversed, as shown in Figure 9,so that its spline 30 Will drive the gear 36 which, through gears 4n. dlM. rotates in the opposite direction to gear 33. By conneeting the shaft28 to drive the oppositely rotating gear 36, with the oppositely runningcrank-shait, the entire auxiliary equipment Will function in its properdirection. notwithstanding the change indirection of rotation 01? theengine.

.If the direction of rotation of the engine should be changd, say, fromright to left, or vice versa, it is only necessary to reverse the shaft28 endwise to drive either of the oppositely rotating gears 33, 36 todrive the elements of the auxiliary equipment in the single directionfor which they are designed. To accomplish this, it is only necessary toremove the head 28 and casing 21 and the mechanism carried thereby fromthe crankcase 20 to provide access to shaft 28 for its reversal.Similarly, by reversing the shaft 28, the rotary uni-directionalauxiliary equipment may be driven in the correct direction to funetionwhen applied to either a right or left-hand engine. Therefor, the entireauxiliary equip- Titre invention also exemplifles driving mecn-' anismfor the auxiiiary equipment, which is adapted to be connected to a motoroperating in either direction with a minimum of labor. In

'aircraft operation, the same 'auxiliary equipment thus becomes adaptedforeither right or left engines, without change in structure, andbyselective position 01 the shatt 28 between the drive mechanism' forthe equipment and the the thrust stresses developed by the rotor et theimpeller are economically applied.

The invention is not to be understood as restrictedto the details set'forth.since these niay 'be modifled within the scope of theappendedclims-without departing from thesphit and scope of theinvention.

Having thus deacribed the invention. what we claim as new and desire tosecure by Letters Patent is:

1. In an accessory unit for internal (20' bustion engines, thecombination dt 8. ho in adapt ed for attachment to one end 013 the gin 5casing, accessory driving gearing comp ing a pair of gears, a.nintermediate gear rixeshing with the pair of gears for oppositerotation, and an endwise reversible shaft adapted to connect anengine-driven shaft with either of the pair of gears to drive thegearing in the same direction -from either a right or leit-hand engine.

2. In ,an accessory unit for interna] combastion engines, thecombination of a. housing adapted for attachment to one end of theengine casing, accessory driving gearing comprising a pair of bevelgears, an intermediate bevel gear connecting the gears for oppositerotation, and

an-endwise reversible shaft adapted to connect an angine-driver: shaftwith eitherpof the pair 01 gears to drive the gearing in the samedirection from either a right or.lfthand engine.

3. In an accessory unit for internai combustion engines, the combinationof a housing adapted for attachment to one end of the engine casing,accessory driving gearing comprising a. pair of coaxial bevel gears, anintermediate bevel gent connecting the pair of gears for oppositerotation,- a. series of radial shatts, a bevel gear on each radial shattmeshing with each of the coaxial-mars, and a shaft coaxial with thecoaxial gears, and accessories driven by said shafts respectively and anendwise reversible sh aft adapted to connect an engine-driven shatt witheither 01 the pair of coaxial gears to drive the gearing in the samedirection from either a right or lft-hand engine.

SAMUEL HOFFMAN.

